1. Field of the Invention
The present invention relates to a method of using light waves for precisely positioning an object in space for use in precision manufacturing fields such as the electronics industry and the precision machinery industry, and to an apparatus for implementing the method.
2. Description of the Prior Art
Methods are recently being developed that utilize quasi white light interferometry for positioning control and dimensional metrology applications in industries such as the electronics, precision machinery and biotechnology industries, using low coherent light semiconductor lasers or solid state lasers as light sources. Methods are also being developed that use a plurality of lasers, each with a different wavelength, to improve the precision with which an object can be positioned in space.
However, with respect to the former methods, low coherent light semiconductor lasers or solid state lasers are not capable of delivering the type of spectral band width required of a light source used for quasi white light interferometry, while in the latter methods in which a plurality of light sources are employed, synchronizing two or more laser light sources necessitates stabilizing the light sources and using the light sources in a stable environment, which limits the applicability of the methods.
Moreover, in both types of methods the light sources have a relatively narrow spectral band width in the order of 10 nm, so coherence is relatively good, resulting in a large number of interference fringes, in addition to which the interference fringes have flat profile lines, making it difficult to identify the zero order white light interference fringe. Hence, spatial positioning precision is poor.
An object of the present invention is to provide a method and apparatus that readily enables an object to be positioned in space with high precision, using quasi white light interferometry that employs a single low-coherence laser as the light source.